Rail flaw detector recording mechanism



Oct. 24, 1950 H. c. DRAKE 2,527,001

RAIL FLAW DETECTOR RECORDING MECHANISM Filed April 14, 1949 2 Sheets-Sheet l FIGJ lllll II II lllllllllllm INVENTOR.

4 HARCOURT C. DRAKE ATTORNEY.

Oct. 24,, 1950 c, DRAKE 2,527,001

RAIL' FLAW DETECTOR RECORDING MECHANISM Filed April 14, 1949 2 Sheets-Sheet 2 {PER FT mm.

I r3 PER F1:

RAIL

..L" 2 PER F1: RAIL s PER Ft RAIL U PER FT. RAIL INVENTOR. I I nmcoun'r c. DRAKE AT TOR NE Y.

gam x Patented Oct. 24, 1950 RAIL FLAW DETECTOR RECORDING MECHANISM Harcourt C. Drake, Hempstead, N. Y., assignor to Sperry Products, Inc., Danbury, Cnn., a corporation of New York Application April 14, 1949, Serial No. 87,433

(01. s4s -3s 3 Claims.

This invention relates to rail flaw detector recording mechanisms and is particularly designed for application upon the type of detector mechanism employed on the Sperry rail flaw detector car. This car operates upon the principle of energizing the rail with flux, as, for instance, by passing current through the rail toestablish an electromagnetic field surrounding the same and exploring said field by inductive means to discover any irregularities caused by the presence of fissures or other discontinuities in the rail. The particular problem which presents itself here arises from the fact that rails are joined by angle bars, bolts, etc., which joints constitute in themselves irregularities in the rail which will cause variations in the flux in the same manner as an internal fissure. Therefore, as the detector car rides along the rail, the detector mechanism in passing over a rail joint gives rise to a large number of closely bunched indications on a recording tape, which indications are not distinguishable from one another nor from the indications which may be caused by an internal defect in the rail. As a result. should an internal fissure occur in the rail within the region of the angle bar or adjacent to the ends of the angle bar, it would be impossible to distinguish such fissure from any other indications.

It is the principal object of this invention to provide a. method and means for enabling a detector car to detect internal fissures within the region affected by the angle bar.

Further objects and advantages of this invention will become apparent in the following detailed description thereof.

In the accompanying drawings,

Fig. 1 is a side elevation of a portion of a rail fissure detector car having my invention applied thereto.

Fig. 2 is an enlarged front elevation and wiring diagram of a mechanism for effecting accelerated speed of the indicating chart at the joints.

Fig. 3 is an enlarged vertical section through an overrunning clutch employed in the Fig. 2 mechanism.

Fig. 4 is a portion of an indicating chart illustrating diagrammatically the principle underlying this invention.

Referring to Fig. 1 of the drawngs, there are shown the parts of a standard Sperry rail fissure detector car which includes a car body In operating along the rails R. Fissure detection is accomplished by energizing the rail with flux by jsponsive members 22 and 22' to compensate for erator G within the car body, supplying current to spaced current brushes l I and I2 supported upon the current brush carriage l3 which when in lowered or effective position is adapted to ride upon the rail by means such as wheels IS. The current brush carriage I3 is normally held in elevated or ineffective position by means of springs, not

shown, and cables l6, but when it is desired to lower said carriage, fluid pressure such as compressed air is supplied to the cylinders I! to force out pistons 58 which are pivotally connected at is to the current brush carriage l3. The current passed through the rail by way of spaced brushes H and I2 will establish an electromagnetic field which may take the form of a plurality of pairs of opposed induction coils 22, 22' supported in a housing 23 at a constant distance above the rail surface by means of a carriage 24. Said carriage 24 is mounted on current brush carriage l3 by means of loosely fitting bolts 25 and springs 26 to permit said carriage 24 while riding on the "rail on means such as wheels 21 to move inde- 'pendently of carriage l3 so that the said carriage 24 may at all times maintain parallelism with the rail surface regardless of irregularities thereof. The coils 22, 22' normally cut the same number of lines of force but on entering a region of flaw, first one coil of each pair and then the other will cut a different number of lines of force to generate a differential E. M. F. which after bein suitably amplified by amplifiers such as amplifiers A and A may be caused to actuate pens P and P operating on a chart C. At the same time that the pens are actuated there is actuated also marking means which may take the form of a paint gun 30 mounted on the current brush carriage l3 a sufficient distance behind the flaw rethe movement of the car and for the lag in operation of the paint gun.

Since the mechanism described above is duplicated for the other rail there will be actuated a total of four pens all of which may co-act with the same chart C. The pens will draw lines I and II for one rail and lines III and IV for the other rail. The chart may be driven from the car axle as will be described more fully hereinafter so that the pens normally draw four straight lines along the chart except where the electromagnetic field is distorted either by fissures within the rail or by the irregularities introduced by the rail joints, 1

As stated in the introduction hereto, the joints which hold the rails together comprise angle bars 32, bolts 33, and additional members, all of which serve to deflect the current passing through the rails and vary the electromagnetic field surrounding the same. The irregularities of the angle bar will cause the detector coils to pick up a large number of variations in the electromagnetic field and this in turn will cause the pens to record upon the chart C a large number of closely bunched indications. Since the current deflection caused by the angle bar commences a considerable distance in advance of the bar and extends its infiuence for a similar distance beyond the leaving end of the bar, it will be understood that there is a considerable portion of rail within which it will be difiicult to discover any internal defects because any indication of variation in flux caused by the internal defect will be merged with, and be indistinguishable from, the large number of indications set up by the angle bar within the region affected thereby. However internal defects do occur in this region and it is desirable to detect them.

To achieve the result described above, applicant resorts to the following steps: First, the plurality of pairs of detector coils 22 and 22 are arranged in tandem and the coils of each pair are similarly arranged. However, whereas coils 22 are positioned with their axes transverse of the longitudinal dimension of the rail, coils 22' are arranged with their axes normal to the rail tread. Furthermore, the diameter of coils 22 is relatively small compared with the rail width and these coils are positioned substantially centrally of the rail head so as to be relatively little affected by the lateral distortion of the electromagnetic flux caused by the rail joint. Therefore coils 22 will be able to test into the angle bar region without being appreciably affected by the distortion.

The second step of this method consists in causing the transverse coils 22 and the vertical coils 22 to actuate separate pens P and P through separate pen actuating mechanisms. Thus While the pen P is shown actuated by relay D and pen P by relay 5|, the latter may represent diagrammatically a device such as a brush oscillograph in which the degree of movement of pen P is a function of the degree of energization of coil 5| or of the voltage output of amplifier A, Thus while the pen P will be actuated a relatively constant distance for any output of amplifier A which is sufficient to energize coil 56 to attract pen P against the action of a suitable spring 52, pen P will be actuated proportionately to the energy output of amplifier A and therefore energy input into the brush oscillograph.

The records which the two pens make in response to a variation in flux will be fundamentally different, as shown on the lines I, II, III, and IV. Whereas the actuation of pen P by coils 22 is substantially constant, the actuation of pen P by coils 22 will be in the nature of an oscillograph recording where the degree of actuation of the pen is proportional to the voltage.

The advantage of having the two recording systems is illustrated at positions H and H and F and F on graphs I and II. The graph at position is a series of indications typical of those which are produced by a joint on the non-proportional recorder which actuates pen P. These indications are a series of substantially rectangular markin s and it will be seen that the presence of a defect within this region does not appear any difierent from that of the joint parts. However by reference to the proportional output graph of pen P in the region F there occurs an indication H which can be recognized by those skilled in the art as the typical output from an internal defect. This typical output consists of a small positive pulse 55, a relatively large negative pulse 55, followed by another small positive pulse 51' similar to pulse 55. Note that the remainder of the indications in the region F due to the joint do not produce this typical flaw responsive output 55, 56,

5'1, and thus while in the non-proportional record it is impossible to distinguish the transverse fissure H from the other markings constituting the joint F, in the proportional output record it is possible to distinguish the indication of the internal defect output from the indications made by the other parts of the rail joint.

Examination of other joints such as K, K, and L, L which on the non-proportional record give the same type of output as the joint F, do not indicate the presence of a fissure because on examination of the proportional record K and L there cannot be found the typical output due to a fissure as shown at H.

The final step in applicants method consists in the following: Heretoiore it has been customary to drive the chart C from the car axle at a relatively slow rate on the order of per foot of travel of the car. However with such slow travel of the chart it would not be possible for the proportional output indicator to yield a recognizable graph such as 55, 56, 51, owing to the fact that the distance spanned by this indication would represent so small a distance on the chart that there would be an indication such as M where the entire record of that fissure takes place in practically a straight line. It is therefore necessary to have a relatively fast movement of the chart if the proportional output record is to give an indication that is readily readable by an operator during the movement of the chart. How ever, continuous movement of the chart at such a rapid rate would be undesirable because it would be difficult for an operator to follow the markings of both rails at such a rapid rate. Since however the indications due to defects in the rail in the regions between joints are readily distinguishable on the non-proportional output indicator, as shown at M on line IV, it is desirable to move the chart at a relatively rapid rate only in the region of the joints for it is in this region that the markings due to fissures become indistinguishable from the markings due to joints. Therefore I have provided means for driving the chart normally at a relatively slow speed, i. e., on the order of E, per foot of rail in the region between joints, and driving the chart at a relatively rapid rate, i. e., on the order of per foot of rail in the region of the joints.

To accomplish the above purpose I provide a two-speed drive for the chart driving shaft 50 by interposing between the car axle BI and the shaft 60 a two-speed gear arrangement controlled by means which are responsive to the presence of joints. These means may take the form of a pair of pivoted joint fingers 62 and B3 pivoted at 64 and 65 on the current brush carriage !3, in advance of and to the rear of the current brush carriage. Finger 62 is positioned sufiiciently in advance of coils 22 so as to engage the projecting angle bar just before coils 22' enter the region of flux afiected by the joint. Similarly finger 63 is positioned sufficiently to the rear of coils 22 so that said coils will have passed beyond the region of flux affected by the angle bar by the time finger 63 drops ofi the leaving end of the angle bar. Finger 63 is positioned so as to engage the angle bar before finger 62 leaves the bar. When finger 62 engages the bar it will close a set of contacts 68 which will close a circuit through a relay 59, said circuit including a battery 10, to cause the relay 69 to attract armature H in the form of a lever pivoted at 12 to cause clutch members 13 to engage. Prior to engagement of clutch parts 13 the car axle 6| drives through gear 15 and gear 16 to the shaft 60. This is the gearing which will produce a movement of the chart at the relatively slow rate, on the order of 1% per foot. However when finger 62 engages the angle bar to close contact 68 clutch I3 is engaged and thereafter the drive from axle 6| takes place at the more rapid rate through gears H and 18 to shaft 60 to drive the same at the relatively rapid rate, on the order of per foot of rail. The clutch parts 13 will remain engaged as long as fingers 52 and 63 ride on the angle bar. When finger 53 leaves the angle bar, relay 69 Will be de-energized and spring 80 will disengage the clutch parts 73 to restore the slow drive through gears 15, 16. To permit the rapid drive to take control when the clutch parts 13 are engaged gear 15 may be provided with any well-known form of overriding or free-wheeling clutch as shown in Fig. 3, consisting of the well-known ball and wedge one-way engagement and the other way release.

Thus by reference to Fig. 4 it will be seen that in the region of joints L, L, F, F, and K, K the chart has moved at the relatively rapid rate of per foot of rail while in the intermediate portions, such as M, M, the chart has moved at the relatively slow rate of per foot of rail.

Having described my invention what I claim and desire to secure by Letters Patent is:

1. In a rail flaw detector car adapted to travel over rails connected by joints, said car having means for energizing the rail with flux, means responsive to variations in said flux caused by defects in the rail, said responsive means responding also to variations in said flux caused by the region of a joint, a chart, a pen cooperating with the chart, means for actuating said pen by said flux responsive means, means for normally driving said chart at relatively slow speed with respect to the speed of the car, means for driving said chart at relatively high speed with respect to the speed of the car, means responsive only to a joint, and means actuated by said last named joint responsive means while responding to a joint for rendering said second chart driving means effective and said first chart driving means inefiective.

2. In a rail flaw detector car adapted to travel over rails connected by joints, said car havin means for energizing the rail with flux, means adapted to generate an E. M. F. in response to variations in said flux caused by defects in the rail, said responsive means responding also to variations in said flux caused by the region of a joint, a chart, a plurality of pens cooperating with said chart, means for actuating one of said pens to a substantially constant degree in response to said induced E. M. F., means for actuating another of said pens to a degree proportionate to said induced E. M. F., means for normally driving said chart at relatively slow speed with respect to the speed of the car, means for driving said chart at relatively high speed with respect to the speed of the car, means responsive only to a joint, and means actuated by said last named joint responsive means While responding to a joint for rendering said second chart driving means eilective and said first chart driving means ineffective.

3. In a rail flaw detector car adapted to travel over rails connected by joints, said car having means for energizing the rail with flux, a plurality of means adapted to generate an E. M. F. in response to variations in said flux caused by defects in the rail, said responsive means responding also to variations in said flux caused by the region of a joint, one of said last named means comprising a pair of coils positioned with their axes transverse of the rail, another of said last named means comprising pair of coils positioned substantially vertically with their axes normal to the rail tread and substantially centrally thereof and having a diameter relatively small compared to the width of the rail, a chart, a plurality of pens cooperating with said chart, means for actuating one of said pens to a substantially constant degree in response to the E. M. F. in-

duced in said transverse positioned coils, means for actuating another of said pens to a degree proportionate to the E. M. F. induced in said vertically positioned coils, means for normally driving said chart at relatively slow speed with respect to the speed of the car, means responsive only to a joint, and means actuated by said last named .joint responsive means while responding to a joint for rendering said second chart driving means effective and said first chart driving means ineffective.

HARCOURT C. DRAKE.

No references cited. 

